Abstract: A device and a method for reading a mechanical numerical totalizer meter having a plurality of decadic wheels is disclosed. The device includes a light source for illuminating a portion of a decadic wheel, a sensor for detecting a change in the intensity of light reflected by the illuminated portion of the decadic wheel and for linearly scanning the portion, a processing unit, connected to the light source and the sensor, for processing the change in light intensity detected by the sensor so as to determine the change from one numerical figure of the decadic wheel to the next numerical figure and to translate the change into at least a pulse signal; and a housing containing the light source. The sensor and processing unit, are suitable for constituting a darkroom and having an opening facing the meter.

Abstract: The apparatus for estimating the richness of the mixture admitted into each of the n combustion chambers of an engine having injectors comprises a sensor (26) supplying an output signal that varies in substantially linear manner with richness and that is placed at the junction point between the exhausts from the chambers, and also comprises calculation means. These means store a model of the behavior of the exhaust at the junction point based on the assumption that the richness at the junction point is a weighted sum of contributions from the exhausts from the individual chambers, with the weighting coefficient being smaller with increasing age of the combustion in the chamber, and serving on each pass through top dead center to estimate the air/fuel ratio on the basis of the measured values and of the model.

Abstract: The method of diagnosis determines the state of deterioration of an exhaust gas stoichiometric composition sensor placed downstream of a catalytic converter. The catalytic converter is mounted on an exhaust manifold of an internal combustion engine supplied with an air/fuel mixture, while the sensor generates an output signal correlated with the stoichiometric composition of the mixture. The method comprises the phases of registering a temperature signal correlated with the temperature of the engine; determining the operating range of the engine; determining the stoichiometric composition of the air/fuel mixture; and effecting a hot diagnosis should the temperature signal be greater than a preset reference value, the engine be in the idle operating range and the sensor register a weak stoichiometric composition of the mixture. The hot diagnosis comprises the phases of generating control signals for the engine and of gauging the output signal from the sensor.

Abstract: The efficiency of a catalyser is evaluated starting from output signals of two lambda probes disposed upstream and downstream respectively of the catalyser. In particular, a signal obtained by calculating the difference between the time averages obtained by integration and subsequent division for the duration of an integration window of output signals of these probes is used as the signal indicative of efficiency.

Abstract: Electronic system for calculating injection time in which an electronic unit with microprocessor receives as input a multiplicity of signals measured in the engine and a signal proportional to the engine load, for example a signal generated by a pressure sensor arranged in the intake manifold of the engine. The electronic unit comprises a circuit for compensating for the delay times due to the response inertia of the engine load sensor, the conditioning (filtering, conversion and processing) of the load signal and physical actuation of the injection. The electronic unit also comprises a circuit for the dynamic compensation of the "film/fluid" effect.

Abstract: An electronic concentration control system in which a first exhaust gas composition sensor located in an exhaust pipe downstream from a catalytic converter is connected to an input to a P.I. circuit which generates a control output signal comprising a succession of opposing triangular ramps. The system includes a second exhaust gas composition sensor located in the exhaust pipe upstream from the catalytic converter generating a signal which is fed to a proportional integral circuit whose integrating and multiplying coefficients are altered on the basis of the control signal. The system includes a diagnostic circuit which checks the efficiency of the first and second sensors.

Abstract: An electronic concentration control system in which a first exhaust gas composition sensor located in an exhaust pipe downstream from a catalytic converter is connected to an input to a P.I. circuit which generates a control output signal comprising a succession of opposing triangular ramps. The system includes a second exhaust gas composition sensor located in the exhaust pipe upstream from the catalytic converter generating a signal which is fed to a proportional integral circuit whose integrating and multiplying coefficients are altered on the basis of the control signal.

Abstract: A system for controlling the fuel delivery of an electronic injection system, whereby a processing unit determines the amount of fuel to be injected for achieving a substantially correct stoichiometric air/fuel ratio; which value is subsequently corrected by a coefficient calculated by integrating a signal comprising a signal supplied by a sensor located in the exhaust manifold of the engine and presenting a transfer function comprising a nonlinear characteristic and a delay seriously affecting system response. The system also comprises a processing unit for simulating the transfer function of the engine-sensor system and generating a signal simulating the signal actually produced by the sensor but minus the delay introduced by the sensor and the system; which signal is used for producing a correction signal which is added to the signal generated by the sensor for compensating the delay and so improving the dynamic response of the system as a whole.